It is the long-range purpose of this project to understand the biological role and mechanisms regulating the nucleotides, cyclic AMP and cyclic GMP in Escherichia coli. The focus of interest during the current year was to study the mechanism by which a sugar transport system known as phosphoenolpyruvate: glucose phosphotransferase system regulates the activity of adenylate cyclase. We found that the membrane-bound sugar recognition proteins of this transport system are essential for adenylate cyclase regulation by glucose but do not influence the activity of the enzyme in the absence of glucose. BIBLIOGRAPHIC REFERENCES: Peterkofsky, A.: Regulation of Escherichia coli adenylate cyclase by Phosphorylation-Dephosphorylation. Trends in Biochemical Sciences 2: 12-14, 1977. Peterkofsky, A.: The Mechanism of Regulation of Escherichia coli Adenylate Cyclase. In: Abou-Sabe, M. (Ed.): Cyclic Nucleotides and the Regulation of Cell Growth. Dowden, Hutchinson and Ross, Stroudsburg, Pa., pp. 27-35, 1977.